docs: def get_residue_annotations(self, start_resnum, end_resnum=None):
          """Retrieve letter annotations for a residue or a range of residues
  
          Args:
              start_resnum (int): Residue number
              end_resnum (int): Optional residue number, specify if a range is desired
  
          Returns:
              dict: Letter annotations for this residue or residues
  
          """
          if not end_resnum:
              end_resnum = start_resnum
  
          # Create a new SeqFeature
          f = SeqFeature(FeatureLocation(start_resnum - 1, end_resnum))
  
          # Get sequence properties
          return f.extract(self).letter_annotations